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| Influence of passivation on soil properties and bioavailability of cadmium in soils |
| Received:July 19, 2020 |
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| KeyWord:passivator;cadmium contamination;soil properties;aggregates;bioavailability |
| Author Name | Affiliation | E-mail | | WU Xiao-wei | College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China | | | ZHAI Wen-jun | College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China | | | GAO Chao | College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China | | | RONG Sa-shuang | College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China | | | GUO Xiao-biao | Hebei Research Center for Geoanalysis, Baoding 071051, China
Key Laboratory of Mineral Resources and Ecological Environment Monitoring, Hebei Province, Baoding 071051, China | | | ZHAO Hui-wei | National Semi-Arid Agricultural Technology Research Center, Shijiazhuang 050051, China | | | LIU Wei | College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China | auhlw80@126.com |
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| Abstract: |
| Three soil passivators hydroxyapatite(HAP), wheat biochar(WB), and mercapto-modified palygorskite(MPG) were selected for this study. Their effects on soil pH, EC, microaggregates, and Cd availability in the soil were investigated using the dynamic monitoring method. Meanwhile, the passivation mechanisms were explored using X-ray diffraction analysis(XRD) during the processes of in situ immobilization remediation of Cd-contaminated soil. Our results showed that, compared with the control group, the proportion of <2 mm and 2~20 mm aggregates increased on the 5th day of passivation, whereas the proportion of >20 mm aggregates gradually increased with the prolongation of passivation time. In addition to the MPG treatment, the application of passivators all had significant effects on soil pH and EC. When comparing the passivation effects of the three passivators, MPG exhibited the best repair effect. At 40th day, the DTPA-Cd content of the MPG treatment group was 3.01 mg·kg-1 lower compared to that of the control group. Correlation analysis showed that HAP and WB groups affected DTPA-Cd content by changing soil pH, and that the stabilization of soil Cd ions in the HAP and MPG treatment groups caused a change in the proportion of each particle size aggregate. The Cd immobilization by HAP resulted from precipitation, with the presence of Cd3(PO4) 2 confirmed using XRD. Considering the effects of available soil Cd concentrations and physicochemical properties, MPG can be used as a preferred passivator for the in situ passivation of alkaline soil. |
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